In loading marine vessels such as a ship or barge with a liquid cargo, it is necessary that the marine operator in charge of the loading operation be able to look into the tank and view the level of the product as is rises. Heretofore, it has been the common practice of the tankerman in charge of the loading operation to open certain hatches and ullage tubes on a barge whereby he could view the increase as the product level came into the barge and whereby he could use a gauging device to gauge the product as it came in. With the new Federal Regulations promulgated by the U.S. Coast Guard to control the emission of volatile organic compounds, such previous methods are no longer available because during the loading operation hazardous vapors would be emitted from the barge as the barge is loading. One of the problems to be overcome involved how to gauge the level of the product as well as how to see into the cargo tanks. A number of sight glasses were developed. Each of these required for installation that the barge be in a gas-free state or that the cargo dome be removed from the barge and brought ashore whereby modifications could be made. These modifications in most cases require the use of a burning torch or welding rod to cut out and insert a new foundation or fixture to which a viewing portal could be attached.
Various types of viewing portals have been heretofore available commercially. One is the VP Vu Gage Syste manufactured by Victor Pyrate Limited in Great Britain and sold and distributed in the U.S. by W. B. Arnold Co., Inc., West Caldwell, N.J. These viewing devices are adapted to be affixed to existing ullage tubes in the dome lid or cover of each cargo compartment. The viewing devices are manufactured from cast bronze with a glass cover and can be attached to the ullage tubes with hinges and wing nuts. These devices are adapted to be welded into the dome of the cargo tank hexdome. Pins are used to affix the hinges and the wing nut and the view gauge can then be closed and secured and made vapor tight. This type of viewing gauge affords two means of access to the tank. One is by uncovering the glass viewing port, you can see into the tank and you can look down into the tank to the bottom and you can also use a secondary means of light, either flashlight or the use of a mirror, to aid in illuminating the area inside the tank so you can get a visual viewing of the product level as it rises. In this arrangement, the tankerman would normally use the rungs of the ladder in the tank to determine the level of the cargo. He would normally count down from the deck the number of rungs, knowing how many rungs there were, and he could tell if the tank were approximately 1/4, 1/3 or 1/2 full or at whatever level it might be. Since this viewing gauge was hinged, the tankerman could open the cover and then also look inside the tank when non-volatile organic compounds were being loaded or when the tanker was in an area which did not require reduction of the vapors when loading volatile organic compounds. If this were the case, a flame screen could also be installed in the viewing device. A flame screen is a device which prevents flames from entering the cargo tank that is being loaded should a fire occur on the deck of the vessel. Viewing devices with hinged covers are also necessary to allow for the venting of the vapors in the atmosphere of the tank during loading if there is no other means of evacuating the vapors from the tank. With only a single viewing port, there are times when, such as on a cloudy day or in the evening, it is difficult for the tankerman on the deck in charge of the loading operation to view the level of cargo in the tank. If it becomes necessary to add a second viewing device this time the cost becomes prohibitive because it is necessary to remove the domes or gas-free the barge in order to perform a welding operation.
Accordingly, it would be desirable to be able to install a viewing device in a relatively simple manner without the need of a welding operation and without the removal of the domes or the necessity of gas-freeing the barge.
It is an object of the present invention to provide an improved ullage tube viewing device for visual checking of liquid cargo levels without releasing hazardous vapors and a method of quickly installing the same in the absence of heat, i.e. a welding operation, so as to eliminate the necessity for removing the domes or gas-freeing the barge which results in a loss of time for normal barge use.
It is a further object of the invention to provide a viewing device which when placed in the open end of the ullage tube provides a vapor tight and secure seal around the periphery of the viewing device and supports the viewing glass of the viewing device substantially flush with the end of the ullage tube thereby preventing water or ice accumulation on the viewing glass thus making the viewing device unusable.